What to look for when buying binoculars
Nandagopal Rajan October 13, 2012We have all seen and used binoculars, but not many of us actually take the plunge and buy one. This is partly because we don't have a specific use for the product and find the need to have one only when we are on a vacation, that too on a scenic spot. But there are many people who are very serious about their binoculars, among them sports lovers, nature enthusiasts and bird watchers. These users are clear about the specifications they need while buying a device. But what about the average user? Here is a guide to selecting binoculars.
WHAT TO LOOK FOR
The magnification of a binocular is the number that is written with the x. So if the binocular says 10x, it means it magnifies the subject ten times. For instance, a bird 1,000 metres away will appear as if it was at a distanc e100 metres away as see with the naked eyes. The best magnifications for regular use are between 7x and 12x, anything beyond and it will be tough to manage without a tripo
2. Objective Lens Diameter
The objective lens is the one opposite the eye piece. The size of this lens is crucial because it determines the amount of light that enters the binoculars. So for low light conditions, you get better images if you have a bigger diameter objective lens. The lens size in mm comes after the x. A ratio of 5 in relation to the magnification is ideal. Between an 8x25 and 8x40 lenses, the latter creates a brighter and better image with its bigger diameter.
3. Lens Quality, Coating
The lens coating is important because it reduces the amount of light reflected and allows the maximum amount of light to enter. The quality of the lens, meanwhile, ensures the image is aberration free and has better contrast. The best lenses work better in low light conditions as they transmit more light. They also ensure that the colours are not washed out or distorted. Users with spectacles should look for a high eyepoint.
4. Field of View/Exit Pupil
FoW refers to the diameter of the area seen through the glasses and is expressed in degrees. The larger the field of view the larger the area you can see. Exit pupil, meanwhile, is the image formed on the eyepiece for your pupil to see. Lens diameter divided by magnification gives you the exit pupil. An exit pupil of 7mm gives maximum light to the dilated eye and is ideal for use in twilight and dark conditions.
5. Weight & Eye Strain
One should consider the weight of a binocular before buying it. Consider if using the binoculars for a prolonged time tires you. Similarly, use a binocular and see if it is taxing on your eye. While it is difficult to use regular binoculars for more than a few minutes at a time, the high-end ones hardly cause any eye strain and can be used for long hours at a stretch if needed.
Since binoculars are an essentially outdoor products, it is important that they have some degree of waterproofing-this is usually denoted as "WP". While regular models can stay under limited amounts of water for a few minutes, the high-end models are left undamaged even after a couple of hours submerged in water.
The best features for specific uses
1. Entry Level
OLYMPUS 7X35 DPS I S
With 7x magnification, porro (double) prism and central focus this is a good option for the budget- conscious buyer.
CELESTRON UPCLOSE G2 10X50
This porro-prism binocular is also ideal for regular use and comes with 10x magnification and has a multi-coated lens.
NIKON SPRINT IV 10X21CF MB
This compact, lightweight model comes with multi-layer coated lens for a clear and bright image.
NIKON ACTION 7X35CF
Ideal for sports and regular use this model has 7x magnification and a 35mm objective diameter.
NIKON TRAVELITE VI 12X25CF
This compact device is ideal for travel and comes withamulti-layer coated lens and rubber armour coating.
BUSHNELL POWERVIEW 20X50
With porro prisms, this is good for birdwatching and nature watching. It comes with Instafocus adjustment and diopter controller and can be mounted on a tripod if needed.
CELESTRON SKYMASTER 25-125X80
This zoom model is ideal for astronomy thanks to the large aperture and multi-coated lens. Needs a tripod though.
3. HIGH END
STEINER SKYHAWK PRO 10X42
This weatherproof model comes with a 42 mm aperture that delivers impressive luminosity even in low light helped by the special coating technology and high-contrast-optics. Ideal for birdwatchers.
CARL ZEISS CONQUEST 8X30
Despite being compact, this model offers a wide objective diameter and high-detail over long distances.
NIKON MONARCH 12X42DCF
Along with the wide objective diameter, this device has a dielectric, high-reflective, multi-layer prism coating for best light and is filled with nitrogen gas to make it fog-free.
SWAROVSKI HABICHT 10X40 W GA
Swarowski binoculars are at the very top due to their superior optics and exceptional build quality. This model promises extrawide field of view and bright, contrast-rich images.